TOMATO BEDDING PLANT-PRODUCTION IN SOILLESS MEDIA CONTAINING GROUND KENAF (HIBISCUS-CANNABINUS L) STEM CORE

Kenaf stem core particles (2-4 mm diam.) enriched with 5000 mg N l(-1) ammonium nitrate solution substituted successfully for up to 30% volume of vermiculite, perlite or calcined clay in media containing 70% sphagnum peat to produce 'Better Boy' tomato (Lycopersicon esculentum Mill.) bedding plants in 80 cm(3) cells. Shoot dry weights by 36 d after transplanting were greater in media containing kenaf than in proprietary control media (Pro-Mix EX and the Van Wingerden Universal Mix). A second study examined tomato growth responses to increasing kenaf soak solution nitrogen concentration (0 to 5000 mg l(-1)) in two media: 30% kenaf:70% peat or 10% kenaf:10% vermiculite:10% calcined clay:70% peat. Shoot dry weights five weeks after transplanting were unaffected by 1,000 to 5,000 mg N l(-1) in either medium, but by seven or nine weeks after transplanting shoot dry weights increased with up to 5,000 mg N l(-1) in 10% kenaf media and with up to 2,000-3,000 mg N l(-1) in 30% kenaf media. Media containing 10 or 30% kenaf enriched with 1,000 to 5,000 mg N l(-1) generally supported greater shoot dry weights than the proprietary media by seven or nine weeks after transplanting. A third study examined tomato growth responses in 70% peat moss and 30% kenaf of which one-third was soaked in 5,000 mg N l(-1) and two-thirds was soaked in 0, 5 or 25 mg a.i. l(-1) of uniconazole or paclobutrazol growth retardants. Shoot dry weights by seven or nine weeks after transplanting into media containing 25 mg a.i. l(-1) of uniconazole were similar to those in the proprietary media but plants were of improved quality.